Since we are in the low-count regime in most of our detected clusters, we strictly used C-statistics in our fits [1]} and modeled our background instead of subtracting it from the total spectrum. The ICM emission is fit with the apec thermal plasma emission model [2]}, [3]}. The solar abundance table from [4]} is adopted. The Galactic hydrogen absorption is modeled using tbabs [5]}, where the column density \(n_{\rm H}\)  is fixed to \(n_{\rm H,tot}\)  provided by [6]} at the cluster position. This value takes not only the neutral hydrogen into account, but also the molecular hydrogen. The current version of the tbabs model includes the most accurate atomic data available for neutral species (e.g., they consider the smearing of the K-photoabsorption edge via Auger decay)https://pulsar.sternwarte.uni-erlangen.de/wilms/research/tbabs. The spectral fitting was done using Xspec version 12.11.1 [7]}.
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